Air heater



April 12, 1932 D. s. JA coBus I 3,

AIR HEATER Filed Sept. 10, 192'? 2 Sheets-Sheet 1 1 )wENToR I B v M ATTORN EYS April 12, 1932. 3 s JACOBU$ 1,853,684-

' AIR HEATER Filed Sept. 10. 1927 2 Sheets-Sheet 2 OOOOOOOOOOOOOOOOOOOOOOOO00 O00 :0OOOOOOOOOOOOOOOOOOOOOOOO INVEIYOR ATTORNEYS Patented Apr. 12, 1932 UNITED STATES PATENT OFFICE.

DAVID s. JAcoBUs, OF MON'IGLAIR, NEW JERsEY, ASSIGNOR TO THE BABoocx & WILcox 1 COMPANY, OF BAYONNE, NEW JERSEY, A CORPORATION OF NEW JERSEY AIR HEATER Application filed September 10, 1927. Serial No. 218,632. I

This invention relates to a device by which heat may be transferred from a hot fluid to a fluid to be heated without bringing the two in contact with each other. The invention will be described in connection with a device for heating air by means of hot gases, but it is understood that the invention is not restricted to this particular use. The invention will be understood from the description in connection 10 Fig. 1 is a vertical section through an illustrative embodiment of the invention and Fig.

2 is a half section taken along the line 22 of Fig. 1. I

15 In the drawings, reference character 5 indicates the casing of the air heater that may be lined on the inside with a layer of heat in-'.

sulating material 6. A group or bank of ducts 7 which may be in the form of tubes have their lower ends connected to a tube sheet 8, and their upper ends connected to a tube sheet 9 with baflies 10 extending across the ducts or tubes and so arranged so as to cause air to pass a plurality of times across the outside of the same. The cold air inlet is indicated at 11, and a waste gas outlet 12 is located below the lower ends of the tubes 7 with an outlet opening 13 at the side thereof. A soot or dust collecting chamber is located at the lower portion of the device and has openings or ducts 15 through which the'dirt or soot can be withdrawn. The device may be supported upon I-beams 16 at the lower portion thereof, and additional supports 18 that may be I-beams, are also provided above the tube sheet 9. An inlet for hot gases is indicated at 19, the side walls of which are shown at 20 and 21. A group or bank of U- shaped ducts or tubes 22 is located so as to extend across the inlet 19 and a space 23 is left'at one side of the casing 5 above the upper baffle 10, which leads to the inlet ends of the ducts or tubes 22. The outlet ends of the ducts 22 lead into a hot air outlet 24. A support 25 in the shape of an I-beam is provided 'with the accompanying drawings in which.

in the wall 20 above the ducts 22, and a tube plate 26 extends from the support '18 to'the support 25 into which tube plate, the ends of the ducts or tubes 22 may be expanded. A layer of heat insulating material 27 is located on the inside of the tube plate 26 so that access of hot gases to the ends of the ducts or tubes 22 is prevented. a

The operation is as follows: Hotgases that are to be used for heating the air are passed downwardly through the inlet'19 and pass over the outside of the ducts or tubes22, thence through the ducts or tubes 7 and thence through the outlet 13, dust or soot from the same. collecting in the lower chamber 14. At the same time, cold air enters through the inlet 11 and passes along the outside of the ducts or tubes 7, as indicated by the arrows, thence through the space 23 into 7 1 the inlet ends of the ducts or tubes 22 and out of these to the hot air outlet 24. It will thus be seen that the fluid that is doing the heating and the fluid that is being heated are passed in countercurrent directions with respect to each other. By protectingthe plate 26 with insulating material, the dam-- ger'of the expanded joints between the ducts or tubes 22 and the plate being injured and leaking, is eliminated.

With this arrangement, the velocity of the air through the ducts 22 can be made high enough to serve asa proper protection from overheating of the ducts 22without involving an excessive drop of pressure through the air heater. This is because the resistance of the flow of the air over the outside of the ducts 7 can be made low in proportion to the flow resistance through the ducts 22 and considerably lower than if the air should flow through the inside of all of'the ducts at the same velocity as through the ducts 22.

The tubes 22 may be made of a metal which is highly resistant to heat such as chrome at a higher temperature than with ordinary steel, Without burning the tubes 22.

I claim:

In an air heater, two groups of ducts and means to cause a heating gas to pass along the outside of one group and then the inside of the other group and air to pass along the outside of the group along the inside of which the heating gas passes and then along the inside of the other group, the ducts in the hotter zone of the air heater being U- shaped. 7

DAVID S. JACOB-US. 

